Electronic devices use a variety of devices for receiving input signals from users to control the devices' operations. Keyboards, mice, microphones, and cameras are all used to receive data for a variety of devices. In addition, touch screens are becoming ubiquitous as an input mechanism for various devices. Touch screens allow a user to tap or touch a screen, which touch is registered by the device as an input signal. A “touch” can be registered in a touch screen using a variety of technologies (resistive, surface acoustic wave, capacitive, infrared grid, infrared acrylic projection, optical imaging, dispersive signal technology, acoustic pulse recognition, and the like) including those where the surface of the touch screen need not be physically touched, i.e., a close pass can trigger signaling by the touch screen corresponding to a “touch” by a finger, stylus, or other touching item. The location of the touch on the touch screen typically corresponds to a particular input signal to which the device will respond.
With the increasing use of touch screens, especially in mobile devices, the touch screens themselves are exposed to a variety of electromagnetic environments. Thus, certain touch screens may output a variety of noise levels that may be registered by the device as a “touch” even though no touch was intended. To counter this problem, a threshold is typically applied such that a signal from the touch screen is not considered a “touch” unless the signal is above a particular threshold, as illustrated in FIG. 1. The signal 110 from the touch screen has noise level 120 and a high input level 130, which level 130 is considered to be a touch to the extent it is higher than the threshold level indicated by line 140. The static threshold approach, however, can fail in a high noise environment where the noise may often exceed the threshold, as illustrated in FIG. 2. Here, a high noise signal 210 is illustrated with the low noise signal 110. This example high noise signal 210 includes a large sinusoidal aspect such that the peaks X of the no-touch portions of the signal 210 exceed the threshold amount 140 and thereby are considered “touches” by the device even though it is clear that only the highest input signal portion 230 was an intended “touch” input for the device.